using System;

using Org.BouncyCastle.Math;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1
{
	public class DerEnumerated
		: Asn1Object
	{
		private readonly byte[] bytes;

		/**
		 * return an integer from the passed in object
		 *
		 * @exception ArgumentException if the object cannot be converted.
		 */
		public static DerEnumerated GetInstance(
			object obj)
		{
			if (obj == null || obj is DerEnumerated)
			{
				return (DerEnumerated)obj;
			}

			throw new ArgumentException("illegal object in GetInstance: " + obj.GetType().Name);
		}

		/**
		 * return an Enumerated from a tagged object.
		 *
		 * @param obj the tagged object holding the object we want
		 * @param explicitly true if the object is meant to be explicitly
		 *              tagged false otherwise.
		 * @exception ArgumentException if the tagged object cannot
		 *               be converted.
		 */
		public static DerEnumerated GetInstance(
			Asn1TaggedObject	obj,
			bool				isExplicit)
		{
			Asn1Object o = obj.GetObject();

			if (isExplicit || o is DerEnumerated)
			{
				return GetInstance(o);
			}

			return new DerEnumerated(((Asn1OctetString)o).GetOctets());
		}

		public DerEnumerated(
			int val)
		{
			bytes = BigInteger.ValueOf(val).ToByteArray();
		}

		public DerEnumerated(
			BigInteger val)
		{
			bytes = val.ToByteArray();
		}

		public DerEnumerated(
			byte[]   bytes)
		{
			this.bytes = bytes;
		}

		public BigInteger Value
		{
			get
			{
				return new BigInteger(bytes);
			}
		}

		internal override void Encode(
			DerOutputStream derOut)
		{
			derOut.WriteEncoded(Asn1Tags.Enumerated, bytes);
		}

		protected override bool Asn1Equals(
			Asn1Object asn1Object)
		{
			DerEnumerated other = asn1Object as DerEnumerated;

			if (other == null)
				return false;

			return Arrays.AreEqual(this.bytes, other.bytes);
		}

		protected override int Asn1GetHashCode()
		{
			return Arrays.GetHashCode(bytes);
		}
	}
}
